1. Technical Field
Generally, the present disclosure relates to microstructure devices including at least some circuit elements that form an electric circuit portion, wherein a non-galvanic signal and/or energy transfer is implemented in the microstructure device by a wireless coupling mechanism formed on the basis of microelectronic components and manufacturing techniques.
2. Description of the Related Art
The significant progress in the field of semiconductor, micromechanical and microelectronic production techniques has resulted in the development and production of a wide variety of microstructure devices, which have incorporated therein more or less complex electronic circuit portions, possibly in combination with micromechanical and micro optical components in order to perform increasingly complex tasks without using complex peripheral components. Hence, there is an ongoing drive in many technical fields to integrate a variety of functions into a single microstructure device, which may thus significantly simplify the design of complex systems and reduce the production costs thereof. For example, integrated circuits are presently available, which may include thousands or millions of transistors, which in turn may be connected so as to form more complex circuit elements in order to implement any desired circuit configuration. Moreover, there is an increasing demand of combining very different types of circuit portions into a single semiconductor device in order to reduce the number and complexity of peripheral components. In many cases, complex control circuitry is combined with driver circuitry and power electronics which specific manufacturing techniques and circuit designs are devised in order to meet the very different specifications for small signal handling in combination with the processing of high currents and/or supply voltages. In this case, typically very different voltage domains may be provided in the same semiconductor device, wherein the transfer of signals and/or energy may be provided on the basis of a non-galvanic coupling of various circuit portions. Similarly, in many small signal applications data transfer between specific circuit portions has to be accomplished on the basis of a non-galvanic coupling in order to improve the immunity of the circuit portions with respect to any signal interferences and/or provide the possibility of coupling different circuit portions that are operated on the basis of different electrical potentials.
In order to implement a corresponding electromagnetic near field coupling mechanism on chip scale typically an appropriate micro transformer is conventionally provided in the semiconductor chip or within the same package, which also accommodates corresponding semiconductor chips that are to be coupled on the basis of the micro transformer.
FIG. 1a schematically illustrates a circuit diagram in which is depicted the basic concept of transferring energy and/or signals between galvanic-isolated circuit portions. The galvanic-isolated circuit portions may be used for data transfer in digital interfaces, utilizing a galvanic isolation, for instance with respect to different operating voltages, superior dielectric decoupling of the circuit portions and the like. In other cases, energy may be transferred in a wireless manner between the corresponding circuit portions in order to appropriately adapt the supply voltage of one of the circuit portions independently from the electric potential of the other circuit portion. For example, in many applications a supply voltage is used, which is at a significantly different electrical potential compared to the supply voltage level of a control circuit and the like. One important application in this respect is the provision of drive signals and drive energy for power transistors, for instance in motor control systems and the like, in which typically the power transistors are at different potentials from several tenths of Volts up to several hundred or even thousands of Volts, depending on the type of power system to be controlled. Similarly, sensing of voltage and/or current in power applications may typically call for a non-galvanic coupling between the sensing circuit portion and the complex control circuitry. Other applications of a wireless signal and/or energy transfer between circuit portions may include medical instrumentation, such as patient monitoring and the like. In FIG. 1a, circuit portions 110a and 110b are implemented in a semiconductor device 100 on the basis of any appropriate manufacturing technology. The circuit portion 110a may generally represent any type of oscillator in order to provide input power to a micro transformer 120 implemented in the device 100, for instance in the form of one or more primary and secondary coils 120a, 120b, which are electrically isolated from each other depending on the overall device specifications. A corresponding isolation line 120c is schematically illustrated in FIG. 1a. Consequently, in the basic configuration of the device 100 in FIG. 1a, the primary coil 120a of the transformer 120 is connected to the circuit portion 110a and thus represents a part thereof, while the secondary coil 120b is connected to the circuit portion 110b and thus also represents a part thereof. In the example shown, the circuit portion 110b may represent a rectifier circuit in order to provide a substantially DC-based voltage and current for the circuit portion 110b for any further internal or peripheral circuit components (not shown). Typically, the micro transformer 120 has to be operated at moderately high frequencies in the range of several hundred kHz and significantly higher so that the overall size of the transformer 120 and also the number of windings in each of the primary and secondary coils 120a, 120b is compatible with the technology under consideration.
FIG. 1b schematically illustrates the microstructure device according to some conventional approaches in which the circuit portion 110a may represent any appropriate circuitry for receiving and/or conditioning an appropriate input power in order to appropriately operate the micro transformer 120. For example, as shown in FIG. 1b, the circuit portion 110a is configured to receive and provide power to the primary coil 120a in a range of approximately 50-500 mW, while in addition or alternatively the circuit portion 110a is configured to handle small signals, such as data signals, which are to be transferred wirelessly to the circuit portion 110b, which thus represents the output stage of a corresponding wireless data channel. In the example shown, the circuit portion or portions 110a are provided on a specific substrate or semiconductor chip and are connected to the transformer 120, i.e., the primary coil or coils 120a, on the basis of bond wires 111a. Similarly, the circuit portions 110b are provided on a dedicated semiconductor chip or substrate and are connected to the secondary coil 120b by means of bond wires 111b. Consequently, in an actual implementation the circuit portions 110a, 110b and the transformer 120, for instance provided in the form of corresponding metal windings or spirals, are arranged side by side on an appropriate carrier substrate and are connected by well-established wire bond techniques and the composite device may be processed on the basis of appropriate packaging techniques, for instance by providing a lid for the carrier substrate and the like. The individual components of the device 100, i.e., the circuit portions 110a, 110b and the micro transformer 120, are formed on the basis of any desired process technology, for instance on the basis of CMOS techniques wherein the circuit portions 110a, 110b are formed as individual devices in accordance with the corresponding circuit layout and the design rules of the technology node under consideration. Similarly, the power transformer is typically formed in the top metal layer of the corresponding process technique, such as CMOS technology, followed by a specific post processing sequence in which an additional passivation material, such as a polyimide material, may be provided in order to subsequently receive a metal layer that is appropriately patterned into one or more metal windings. Similarly, a plurality of transformers can be implemented, for instance for energy transfer and signal transfer, so that the circuit portions 110a, i.e., circuit portions for energy transfer and signal transfer, and a respective number of circuit portions 110b are provided on the corresponding substrate materials. Similarly, the several micro transformers 120 are provided on one or more dedicated substrates so as to be connected by wire bonding upon packaging the device 100.
FIG. 1c schematically illustrates the microstructure device 100 according to other conventional approaches in which the device 100 may represent a DC-DC converter. In this case, the circuit portion 110a comprises a plurality of switching devices, such as MOS transistors, bipolar transistors and the like, possibly in combination with appropriate control circuitry and drive circuitry in order to appropriately switch the primary coil of the transformer 120. The circuit portion 110b represents a rectifier portion in combination with a voltage regulator in order to provide a desired DC output voltage that is galvanically isolated from the input power supplied to the circuit portion 110a. An optional transformer 120 may be implemented in order to establish an isolated feedback loop for controlling the circuitry 110a on the basis of the output voltage delivered by the circuit portion 110b. 
FIG. 1d schematically illustrates the device 100 in a packaged configuration wherein the circuit portions 110a and 110b are isolated by the transformer or transformers 120, while these components are accommodated by a common package. In this case, the isolation line 120c is also established within a single semiconductor chip, similarly to the situation as described in FIG. 1b in which the isolation line 120c is provided on the basis of the metallization system used to implement the primary and secondary coils 120a, 120b. 
Consequently, in these conventional approaches, an efficient energy and/or data transfer may be accomplished between different circuit portions on the basis of a micro transformer that may be formed on the basis of micro electronic manufacturing techniques. Due to economical demands an increased number of circuit functions is typically to be implemented into a given package size, thereby also triggering a significant reduction of the lateral size of the individual circuit portions which, however, may not be compatible with the conventional configurations of the microstructure device 100, as described with reference to FIGS. 1a-1d. That is, the circuit portions 110a, 110b are appropriately positioned laterally adjacent to the power transformer in order to obtain an appropriate electric connection, for instance by bond wires or by the device internal metallization system.